Empty string exception hint the difference between empty and isset

Empty is to determine if a variable is empty, and empty () returns FALSE if the variable is a non-null or nonzero value. In other words, "", 0, "0″, NULL, FALSE, Array (), Var $var, undefined, and objects that do not have any properties will be considered empty, and if Var is null, it returns TRUE." (1) Number 0; (2) null character; (3) A variable defined as null; (4) A variable defined as false; (5) an empty array; (6) an undefined variable. )

Empty will be judged to be NULL for the variable to return true

Isset determines whether a variable is set and returns TRUE if the variable exists (not null), otherwise FALSE (including undefined). The variable value is set to: null, and the variable is canceled after the return is also false;unset a variable. Note that isset for null value variables, special handling.

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